Xiongwen Wu

Interleukin-33 ameliorates ischemic brain injury in experimental stroke through promoting Th2 response and suppressing Th17 response.

Ischemic stroke causes brain injury with activation of an inflammatory response that can contribute to clinical impairment. As a novel cytokine of the interleukin-1 (IL-1) family, IL-33 has been suggested to be involved in regulating pathophysiology and inflammatory responses in the central nervous system (CNS). However, the role and underlying mechanisms of IL-33 in ischemic stroke remain poorly understood. Here, adult male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) for stroke induction. The MCAO procedure resulted in the enhanced Th1 and Th17 immune responses from 6h after transient cerebral ischemia/reperfusion even up to day 3. Meanwhile, the protein and mRNA level of IL-33 expression was significantly decreased at 6h and 72 h, but not at 24h after MCAO. Moreover, recombinant mouse IL-33 administration substantially attenuated ischemic brain damage and neurological deficit at 24h and 72 h, but not at 6h after MCAO. Interestingly, the reduced CNS inflammation in IL-33-treated MCAO mice may be at least partly due to an induced immuno-shift of Th cells from Th1 to Th2 response and suppressing Th17 immune response. These findings demonstrate that IL-33 can play a protective role after MCAO and may be a new target for therapy of ischemic stroke.

Dimerization of soluble HLA-G by IgG-Fc fragment augments ILT2-mediated inhibition of T-cell alloresponse.

Background. Human leukocyte antigen (HLA)-G, a nonclassical HLA class I molecule, induces a wide range of tolerogenic immunological effects by means of interaction with its inhibitory receptors. However, recent studies show that HLA-G dimer formation is essential to bind to its receptors and exhibit its effects. Methods. In this study, a soluble divalent HLA-G/IgG molecule (sHLA-G dimer) was constructed. Its inhibitory effect on T-cell alloresponse was studied with mixed lymphocyte reaction in vitro, which was set up by mixing inactivated T1 cells with HLA-mismatched peripheral blood lymphocytes in the presence or absence of the sHLA-G dimer. Results. The results show that sHLA-G dimer inhibits T-cell alloresponse by reducing proliferation of both CD4+ and CD8+ T cells and suppressing generation of alloreactive cytotoxic T lymphocytes at nanomole concentration. The inhibition of the sHLA-G dimer is observed to be more effective than that of sHLA-G monomer. Our results also indicate that sHLA-G dimer up-regulates inhibitory receptor ILT2 on alloreactive CD8+ T cells, which contributes to the significant inhibition on T-cell alloresponse. Conclusion. The sHLA-G dimer formed by IgG-Fc fragment shows more inhibitory effects on alloreactive T cells, which may have implications for allotransplantation.

The role of HO-1 in protection against lead-induced neurotoxicity.

Lead is a pervasive and persistent environmental pollutant that exerts deleterious effects on all living organisms and continues to threaten public health on a global scale. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme that mediates antioxidative and cytoprotective effects to maintain cellular redox homeostasis and protect cells from oxidative stress. This study was designed to explore the role of HO-1 in protection against lead neurotoxicity and the signaling pathways involved. Lead acetate (PbAc) exposure resulted in increased HO-1 expression in primary rat hippocampal neurons and SH-SY5Y cells. PbAc-induced intracellular reactive oxygen species (ROS) also increased, and cell viability decreased in SH-SY5Y cells. We further demonstrated that HO-1 could be induced by PbAc through the P38, ERK1/2, and PI3K/AKT signaling pathways in a ROS-dependent manner and through the JNK pathway in a ROS-independent manner. Further investigation revealed that HO-1 overexpression significantly restrained cell apoptosis and ROS production induced by PbAc in SH-SY5Y cells. Moreover, HO-1 knockdown aggravated PbAc-induced cell apoptosis and ROS production. Our results indicated that HO-1 was a novel protective factor that could efficiently inhibit PbAc-induced oxidative stress and cell death in the nervous system, thereby providing the potential therapeutic strategies for the prevention and treatment of lead-related diseases.

Peptide-dependent inhibition of alloreactive T-cell response by soluble divalent HLA-A2/IgG molecule in vitro.

Background. Induction of peripheral tolerance in an antigen-specific manner is a critical goal of transplant biology. The specificity and avidity of multimerized peptide/major histocompatibilty complexes suggest their potential ability to modulate antigen-specific T-cell sensitization and effector functions. Methods. A soluble divalent HLA-A2/IgG molecule (HLA-A2 dimer) was constructed and loaded with a self-protein origin peptide (Tyr368–376) to form a divalent Tyr/HLA-A2 molecule (Tyr/HLA-A2 dimer), which allowed for specific targeting to the epitope-specific cytotoxic T lymphocytes in bulk alloreactive T cells. Alloreactive T-cell response was induced by coculture of Tyr368–376-pulsed T2 cells (T2/Tyr) with peripheral blood lymphocytes of HLA-A2-negative (HLA-A2-ve) sample; five samples of HLA-A2-ve individuals were included in this study. After the coculture in the presence of Tyr/HLA-A2 dimer, the suppression of the dimer on alloresponse was characterized by analyzing allogeneic T-cell proliferation, specific cytolytic activity against the T2/Tyr, and specific Tyr/HLA-A2 tetramer staining. Results. The Tyr/HLA-A2 dimer suppresses alloreactive T-cell response by inhibiting its proliferation and cytotoxicity against specific target T2/Tyr in vitro, and it is interesting that the suppression is peptide-specific. The Tyr/HLA-A2 tetramer staining suggests the reduced function of CD8+ T cell is caused by inhibiting the generation of the epitope-specific alloreactive T cells by the Tyr/HLA-A2 dimer in three samples. Moreover, the existence of epitope-specific but function-negative T cells in the other two samples suggests that another mechanism might exist that is involved in silencing alloreactive responses by the dimer. Conclusion. Peptide-loaded dimers offer a novel approach to induce peptide-specific immunosuppression and may be useful in promoting graft survival.

Serum DKK-1 level in the development of ankylosing spondylitis and rheumatic arthritis: a meta-analysis

To explore the association of serum Dickkopf-1 (DKK-1) levels with the development of ankylosing spondylitis (AS) and rheumatic arthritis (RA) in humans, databases including PubMed, EBSCO, Springerlink, Ovid, WANFANG and China National Knowledge Infrastructure (CNKI) were searched to identify relevant studies. On the basis of rigorous inclusion and exclusion criteria, case–control studies of the relationships between serum DKK-1 levels and AS and RA published before December 2014 were enrolled. Statistical analyses were performed using Comprehensive Meta-analysis 2.0 (CMA 2.0). Seven case–control trials with a total of 300 AS patients, 136 RA patients and 232 healthy controls were included in this study. Meta-analysis results revealed that DKK-1 serum levels were significantly higher in AS patients than in normal controls (standard mean differences (s.m.d.)=0.301, 95% confidence interval (CI)=0.094–0.507, P=0.004), whereas no significant difference in DKK-1 serum levels was observed between RA patients and healthy controls (s.m.d.=0.798, 95% CI=−2.166–3.763, P=0.598). Serum DKK-1 level may be closely related to the development of AS but not of RA.

CD8low T-cell subpopulation is increased in patients with chronic hepatitis B virus infection

Recent studies suggest that CD8(+) T cells with down-regulated CD8 expression (CD3(+)CD8(low) T cells) represented as a distinct phenotype of CD8(+) T cells are increased and linked to disease severity in some chronically persistent infection, such as chronic HIV and parasite infection. However, the role of CD3(+)CD8(low) T cells in the context of chronic HBV infection is poorly understood. In this study, peripheral blood samples of 47 chronic hepatitis B patients and 19 healthy controls were collected and tested for the frequency and phenotype of CD8(low) T cells. The circulating CD8(low) T cells were significantly more frequent in the patients compared to those in healthy controls, and the CD8(low) T cells in the patients expressed less IFN-γ and more mTGF-β1 than those in the controls, suggesting their type-2 polarized and suppressive properties. Meanwhile, the concentrations of plasma soluble HLA class I molecules were found elevated in the patients, and positively associated with the frequencies of CD8(low) T cells. Furthermore, the CD8(low) T-cell frequency in the HLA-A2-positive patients (n=21) was found negatively correlated with the T-cell responsiveness against the HBc₁₈₋₂₇ peptide, the latter was impaired as revealed by IFN-γ Elispot assay. Our findings suggested that a better understanding of the involvement of CD8(low) T cells in chronically persistent HBV infection would add to our knowledge of the impaired T-cell response in the patients.

Demineralized dentin matrix composite collagen material for bone tissue regeneration.

Demineralized dentin matrix (DDM) had been successfully used in clinics as bone repair biomaterial for many years. However, particle morphology of DDM limited it further applications. In this study, DDM and collagen were prepared to DDM composite collagen material. The surface morphology of the material was studied by scanning electron microscope (SEM). MC3T3-E1 cells responses in vitro and tissue responses in vivo by implantation of DDM composite collagen material in bone defect of rabbits were also investigated. SEM analysis showed that DDM composite collagen material evenly distributed and formed a porous scaffold. Cell culture and animal models results indicated that DDM composite collagen material was biocompatible and could support cell proliferation and differentiation. Histological evaluation showed that DDM composite collagen material exhibited good biocompatibility, biodegradability and osteoconductivity with host bone in vivo. The results suggested that DDM composite collagen material might have a significant clinical advantage and potential to be applied in bone and orthopedic surgery.

Allo-restricted CTLs generated by coculturing of PBLs and autologous monocytes loaded with allogeneic peptide/HLA/IgG1-Fc fusion protein.

The graft‐versus‐leukemia effect of allogeneic marrow transplantation suggests the dramatic effect of the allogeneic T cell to eradicate malignant disease. Preparation and adoptive transfusion of tumor‐specific T cells from HLA‐mismatched donors might be expected to circumvent CTL tolerance to the tumor. In this study, a soluble, divalent HLA‐A2 molecule was constructed with the Fc part of human IgG1 and was pulsed with a peptide related to melanoma tyrosinase 368–376 [Tyr368–376 (Tyr)] to form the Tyr/HLA‐A2 dimer, which allowed loading onto monocytes via interaction of the Fc and FcR. The HLA‐A2‐negative (HLA‐A2‐ve) monocytes loaded with the Tyr/HLA‐A2 dimer acted as allo‐APC with copies of a single allogeneic epitope. After coculture of the HLA‐A2‐ve PBLs and autologous monocytes loaded with the dimer, CD8+ cells in the coculture show an obvious proliferation and increased frequency of Tyr/HLA‐A2 tetramer‐stained cells. The sorted Tyr/HLA‐A2 tetramer‐positive CD8+ cells display an elevated cytotoxic activity against HLA‐A2‐positive melanoma cells expressing tyrosinase endogenously (i.e., SK‐Mel‐5) but little against tyrosinase‐negative melanoma cells (i.e., A375). The coculture of PBLs and autologous monocytes loaded with allogeneic peptide/HLA complexes offers a novel approach to expand allo‐restricted, peptide‐specific CTLs, which might be a potential arsenal for treatment of patients with malignant disease, if the tumor‐related epitope were defined.

Soluble MOG35-55/I-Ab Dimers Ameliorate Experimental Autoimmune Encephalomyelitis by Reducing Encephalitogenic T Cells

The MOG35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice is a useful animal model to explore therapeutic approaches to T cell-mediated autoimmune diseases because the dominant T-cell epitope(s) have been defined. It is rational that antigen-specific immunosuppression can be induced by using MHC-peptide complexes as specific TCR ligand(s) that interact with autoreactive T cells in the absence of co-stimulation. In this study, a soluble divalent MOG35-55/I-Ab fusion protein (MOG35-55/I-Ab dimer) was constructed to specifically target the autoreactive CD4+ T cells in the EAE mouse. Intraperitoneal administration of the MOG35-55/I-Ab dimer significantly delayed and ameliorated EAE symptoms by reducing EAE-related inflammation in the mouse CNS and reducing encephalitogenic Th1 and Th17 cells in the peripheral lymphoid organs. We observed that dimer intervention at a concentration of 1.2 nM suppressed MOG35-55 peptide-specific 2D2 transgenic T cells (2D2 T cells) proliferation by over 90% after in vitro activation with MOG35-55 peptide. The mechanisms involved in this antigen-specific dimer-mediated suppression were found to be downregulated TCR-CD3 expression as well as upregulated expression of membrane-bound TGF-β (mTGF-β) and IL-10 suppressive cytokines by the autoreactive CD4+ T cells. Collectively, our data demonstrates that soluble divalent MHC class II molecules can abrogate pathogenic T cells in EAE. Furthermore, our data suggests that this strategy may provide an efficient and clinically useful option to treat autoimmune diseases.

Betulin from Hedyotis hedyotidea ameliorates concanavalin A-induced and T cell-mediated autoimmune hepatitis in mice

Hedyotis hedyotidea has been used in traditional Chinese medicine for the treatment of autoimmune diseases. However, the mechanisms underlying for the effect remain unknown. We previously showed that, among 11 compounds extracted from H hedyotidea, betulin produced the strongest suppressive effect on T cell activation. Here, we examined the hepatoprotective effects of betulin against acute autoimmune hepatitis in mice and the mechanisms underlying the effects. Freshly isolated mouse splenocytes were stimulated with concanavalin A (Con A, 5 μg/mL) in the presence of betulin, the cell proliferation was assessed with CSFE-dilution assay. Mice were injected with betulin (10, 20 mg·kg−1·d−1, ip) for 3 d. One hour after the last injection, the mice were injected with Con A (15 mg/kg, iv) to induce acute hepatitis. Blood samples and liver tissues were harvested at 10 h after Con A injection, and serum transaminase levels and liver histopathology were detected; serum levels of proinflammatory cytokines, hepatic T lymphocyte ratios, and functional statuses of conventional T and NKT cells were also analyzed. Betulin (16 and 32 μmol/L) dose-dependently suppressed the proliferation of Con A-stimulated mouse splenocytes in vitro. In Con A-challenged mice, preinjection with betulin (20 mg·kg−1·d−1) significantly decreased the levels of proinflammatory cytokines IFN-γ, TNF-α and IL-6, and ameliorated liver injury. Furthermore, pretreatment with betulin (20 mg·kg−1·d−1) significantly inhibited the Con A-induced activation of NKT and conventional T cells, and decreased production of proinflammatory cytokines IFN-γ, TNF-α and IL-6 in these two cell populations. Betulin has immunomodulatory effect on overly activated conventional T and NKT cells and exerts hepatoprotective action in mouse autoimmune hepatitis. The findings provide evidence for the use of H hedyotidea and its constituent betulin in the treatment of autoimmune diseases.